气氛对Al-MCM-41热稳定性的影响

研究了在不同气氛(氧气、氮气和氨气)条件下Al-MCM-41的热稳定性能,通过比表面积、孔径分布及X射线衍射对Al-MCM-41热稳定性的研究表明:在不同气氛条件下,Al-MCM-41的热稳定性有很大的差异,在氨气或氮气气氛下,处理温度高达1010℃条件下,Al-MCM-41仍然具有良好的介孔结构,但在氧气中介孔结构热稳定温度不超过900℃。     

Hydrothermal synthesis of CdSe hierarchical dendrites using ionic liquid as template

Well-defined CdSe hierarchical dendrites have been synthesized through a facile and effective hydrothermal method. The as-formed CdSe dendrites possess good dispersity and have an average length of about 1 μm along the trunk. Most importantly, it is found that long-chain ionic liquid [C₁₆mim]Cl (1-hexadecyl-3-methylimidazolium chloride), which can adsorb on the (002) plane of wurtize CdSe driven by the coulomb force, serves as an effective template and plays a critical role for the morphology of the product. Furthermore, the UV-vis spectrum of the CdSe dendrites displays absorption maxima at 296 nm; therefore, the obtained CdSe dendrites might have promising application in blue emitters, gas sensors, and light-emitting devices.     

Esterification of levulinic acid into hexyl levulinate over dodecatungstophosphoric acid anchored to Al-MCM-41

Aluminum-substituted MCM-41 (Al-MCM-41) were hydrothermally synthesised and used as supports to fabricate the mesostructured H₃PW₁₂O₄₀ (HPW) solid acid catalysts via an impregnation method. The influences of various HPW loadings on the structures of the catalysts were verified by X-ray diffraction (XRD), nitrogen physisorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet–visible (UV–Vis) spectroscopy and Fourier-transform infrared spectroscopy (FT-IR) measurements and their acidities were evaluated by infrared of pyridine adsorption (Py-IR) and temperature-programmed desorption of ammonia (NH₃-TPD) measurements. The optimisation of the reaction conditions for levulinic acid esterification with n-hexanol such as the reaction temperature and time, the reactant molar ratio, and the catalyst dosages was performed to maximise the conversion of levulinic acid. The effects of various HPW loadings on the conversion of levulinic acid were investigated under the optimised and harsh reaction conditions. The reusability of the catalysts was also investigated. The results showed that these catalysts retained the hexagonal mesoporous structure of Al-MCM-41 and the Keggin characteristic of HPW, although their textural parameters decreased with increasing loading of HPW. In particular, the catalysts were found to be efficient in the esterification of levulinic acid with n-hexanol, resulting in hexyl levulinate which could replace the petroleum-derived chemical feedstocks.     

Synthesis of Ag-AgBr/Al-MCM-41 nanocomposite and its application in photocatalytic oxidative desulfurization of dibenzothiophene

A series of Ag-AgBr/Al-MCM-41 nanocomposites were synthesized by dispersion of Ag-AgBr on mesoporous silica Al-MCM-41 obtained from natural bentonite. The synthesized Ag-AgBr/Al-MCM-41 composites with Ag nanoparticles growing on the surface of Al-MCM-41 were used for photocatalytic oxidative desulfurization of dibenzothiophene. The physical properties of Ag-AgBr/Al-MCM-41 were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Ultraviolet–visible diffuse reflection spectroscopy (UV–Vis DRS), photoluminescence (PL) emission spectra, and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity results showed that in the presence of 40% Ag-AgBr/Al-MCM-41 photocatalyst the oxidative desulfurization of dibenzothiophene reached the maximum efficiency at 99.22% and the photocatalytic activity still keeps high level after four cycles.     

协同模板机理合成六方介孔分子筛[Ti]-MCM-41

[Ti]-MCM-41介孔分子筛是在空气中采用协同模板机理水热合成出来的,其中Ti离子是处在MCM-41的骨架孔壁中.合成所用硅源为工业级水玻璃,液晶模板剂为十六烷基三甲基溴化铵.对3种基本因素进行了考察,一是搀杂的Ti源不同,分别是四氯化钛和钛酸四丁酯;二是合成时溶液pH值不同;三是合成时Ti/Si摩尔比不同.样品表征分别采用XRD粉末X光衍射、N2吸附-脱附等温线(77K)对样品的结构性能进行了表征.     

Toxicity and biodegradability of imidazolium ionic liquids

Several bioassays have been carried out to analyze the toxicity and biodegradability of several imidazolium ionic liquids (ILs) in aqueous phase. The synthetized compounds consist of an imidazolium cation with two alkyl substituents in positions 3 (R1) and 1 (R2) and a counter-ion. The alkyl substituent R1 has been fixed as a methyl group and the effect of the alkyl chain length (C1-C8) of the other substituent (R2) has been tested. Moreover, the influence of diverse counter-ions A- (Cl-, PF6, XSO4-) has been analyzed. Acute toxicity and EC50 values of each compound in the aqueous solution have been determined by using the Microtox standard procedure. Biodegradability of IL has been determined by measuring BOD5 of aqueous samples containing IL and/or D-glucose and the IL residual content and/or d-glucose concentration after this assay. The viability of the microorganisms used in the BOD5 has been related to the ATP in the samples, measured by a bioluminescence assay. All the ILs tested were not biodegradable in the considered conditions. Besides, it was found that the shorter the chain length of side chain R2, the lower the toxic effect is. On the contrary, the anion has a little effect on the IL toxicity.     

氢氧化铝纳米粒子为模板制备中孔炭

氢氧化铝纳米粒子为模板可以制备中孔炭,改变pH值可以调整炭前驱体溶液中氢氧化铝纳米粒子的大小,结果表明：中孔含量随pH值的升高而增加；当pH值为12时，中孔集中于3-4nm，孔容积为0．108cm^3/g，pH为8时，几乎没有中孔生成。     

Synthesis of high surface area mesoporous carbonates in novel ionic liquid

High surface area mesoporous SrCO₃, CaCO₃ and MnCO₃ with straw-like bundles morphology were synthesized in a novel imidazolium pyruvate ionic liquid. These carbonates were characterized by X-ray diffraction, Fourier transform infrared spectra and transmission electron microscopy. The results revealed that these carbonates have pure orthorhombic and rhombohedral structures, respectively, and the prepared products all show the unique straw-like morphology. Mesoporous properties and high surface areas of SrCO₃(118 m²/g), CaCO₃(43 m²/g) and MnCO₃ (122 m²/g) were also confirmed by the corresponding N₂ sorption analyses.     

Preparation of UV-filter encapsulated mesoporous silica with high sunscreen ability

In this study, a UV-filter encapsulated in a mesoporous silica, MCX-MS, was prepared by the in-situ sol-gel polymerization of tetraethyl orthosilicate (TEOS) with an ionic liquid (IL) as solvent and pore-forming agent and octal methoxycinnamate (MCX) as an additive. MCX-MS was characterized by Fourier transformation infrared (FT-IR) spectroscopy and transmission electron microscopy (TEM). The result of the thermogravimetric analysis (TGA) showed that the amount of MCX encapsulated in MS was about 65 wt.% of MCX-MS. Comparing with that of the free MCX, the SPF value of the MCX-MS-containing sunscreen cream increased by about 57%, indicating significant enhancement of the UV protection ability of MCX by encapsulation in the mesoporous silica matrix. Furthermore, because the average particle size of MCX-MS emulsion droplets was big enough, damage by penetration through the skin is expected to be prevented.     

Spectroscopic properties and amplified spontaneous emission of fluorescein laser dye in ionic liquids as green media

The use of ionic liquids (ILs) as milieu materials for laser dyes is a promising field and quite competitive with volatile organic solvents and solid state-dye laser systems. This paper investigates some photo-physical parameters of fluorescein dye incorporated into ionic liquids; 1-Butyl-3-methylimidazolium chloride (BMIM Cl), 1-Butyl-3-methylimidazolium tetrachloroaluminate (BMIM AlCl₄) and 1-Butyl-3-methylimidazolium tetrafluoroborate (BMIM BF₄) as promising host matrix in addition to ethanol as reference. These parameters are: absorption and emission cross-sections, fluorescence lifetime and quantum yield, in addition to the transition dipole moment, the attenuation length and oscillator strength were also investigated. Lasing characteristics such as amplified spontaneous emission (ASE), the gain, and the photostability of fluorescein laser dye dissolved in different host materials were assessed. The composition and properties of the matrix of ILs were found that it has great interest in optimizing the laser performance and photostability of the investigated laser dye. Under transverse pumping of fluorescein dye by blue laser diode (450 nm) of (400 mW), the initial ASE for dye dissolved in BMIM AlCl₄ and ethanol were decreased to 39% and 36% respectively as time progressed 132 min. Relatively high efficiency and high fluorescence quantum yield (11.8% and 0.82% respectively) were obtained with good photostability in case of fluorescein in BMIM BF₄ that was decreased to ∼56% of the initial ASE after continuously pumping with 400 mW for 132 min.     

Preparation and characterization of ceria nanoparticles using crystalline hydrate cerium propionate as precursor

Ceria nanoparticles were synthesized simply by pyrolysis method using hydrate cerium propionate as precursor. The effect of pyrolysis temperature on the physical properties of ceria was investigated. It was found that the large crystals of precursor cracked to many nano-sized ceria particles on heating, and the medium particle sizes D₅₀ determined by laser scattering (LS) method decreased firstly and then increased with minimum value around 460 nm at calcination temperature of 1000 °C. SEM observations showed that the average particle size of synthesized ceria powders ranged from 20 to 50 nm.     

Using hydrophilic ionic liquids as a facile route to prepare porous-structured biopolymer scaffolds

A simple new methodology to preapre 3-dimensional (3D) porous scaffold of biodegradable polymer was exploited by using hydrophilic types of ionic liquids. The mixture of poly(lactic acid) (PLA) and ionic liquid within dichloromethane solvent was phase-separated during the solvent evaporation, after which the ionic liquid phase was selectively extracted to provide interconnected macropores. The pore sizes of the PLA scaffold were highly dependent on the types of ionic liquids (anion variant), ranging from tens to hundreds of micrometers, and the porosity reached to ~ 85-95%. The ionic liquid-directed technique to prepare porous structure reported for the first time herein will be highly effective in the development of polymer skeletons for tissue engineering biomaterials. In addition, the ionic liquids recovered by a simple extraction with ethanol or water can be reused for subsequent runs without the loss of its physicochemical properties.     

Spherical mesoporous silica templated with ionic liquid and cetyltrimethylammonium bromide and its conversion to hollow spheres

Spherical mesoporous silica was synthesized using a mixture of 1-methyl-3-octylimidazolium chloride and cetyltrimethylammonium bromide as the structure-directing agent. The obtained silica was characterized by X-ray powder diffraction, scanning electron microscope, transmission electron microscope, and ¹³C NMR spectroscopic techniques. The results show that the spherical silica possesses worm-like mesopores and larger mesopores, with the sizes about 6-50 nm. It is very interesting that the spherical mesoporous spheres were converted to hollow ones after reflux in boiling water. The treatment results in the generation of the hollow interior by dissolving the silica core. Meanwhile, the silica shell is well retained, which is confirmed by SEM and TEM images.     

一种松香基双季铵盐和CTAB共混模板介孔SiO2的制备

以一种松香基双季铵盐和CTAB为共混模板,正硅酸乙酯为硅源,通过调节两种表面活性剂的不同用量,在碱性条件下水解制备了SiA、SiB、SiC、SiD4种SiO2材料。采用TGA确定煅烧温度为550℃;SEM照片分析可知SiC、SiD的微观形貌优于SiA、SiB,且为分散均匀的球形颗粒,无团聚;TEM照片分析可知,SiC、SiD为具有介孔结构的球形颗粒;FT-IR确证了SiC、SiD煅烧前后的基本结构;经氮气吸附-脱附实验分析,结果表明,SiC、SiD的孔径主要集中在3.8nm处,比表面积和累积孔体积分别为685.29m2/g、1.22cm3/g和609.73m2/g、0.93cm3/g。     

磺酸基功能化离子液体中水杨酸系列酯的合成研究

合成了6种Brφnsted酸性离子液体,以其作为催化剂,用于水杨酸酯的合成中.实验结果表明,所选离子液体对水杨酸乙酯的合成都具有较高的催化活性,其中[HSO3-pmim][OTf]的催化效果最好.以[HSO3-pmim][OTf]为催化剂,考察酸醇物质的量比、反应时间、反应温度及离子液体的用量对酯化率的影响.最佳实验条...     

双功能性离子液体溶胶-凝胶法制备介孔SiO_2

首先合成了一种新型双功能性离子液体1-甲基-3-(3'-磺酸丙基)咪唑十二烷基磺酸盐([PMIM(SO3H)][C12SO3]),并采用FT-IR、1H NMR和13C NMR对其结构进行了表征;进一步以该离子液体为模板剂和酸源,以正硅酸乙酯(TEOS)为硅源,通过溶胶-凝胶法制备出介孔SiO2,利用TGA和FT-IR研究了介孔材料的形成过程,采用SAXRD、SEM、TEM和氮气等温吸附-脱附等手段对介孔材料的结构形貌进行了表征,并研究了其对Pb2+的吸附性能。结果显示,以[PMIM(SO3H)][C12SO3]为模板剂和酸源制备的介孔SiO2其比表面积、孔容、平均孔径大小分别为1 010m2/g、0.95 cm3/g、3.25 nm,其对重金属Pb2+有很好的吸附性能。     

Surface characterization of BiSbTe thermoelectric films electrodeposited from chlorides aqueous solutions and choline chloride based ionic liquids

Investigations of obtaining BiSb, BiTe, SbTe and BiSbTe films in concentrated chloride aqueous solution (5 M NaCl + 1 M HCl) or in ionic liquid based on choline chloride + malonic acid mixture were reported. The concentrations of Bi, Sb, Te, existing as complex anions due to high Cl⁻ concentration, were within 10–90 mM. The measurements were carried out at room temperature for aqueous medium and 85 °C for ionic liquid. Cyclic voltammetry and electrochemical impedance spectroscopy using Pt electrode were used for investigating the interface process in both electrolytes. The morphology and chemical composition of films deposited on Cu in chloride aqueous solution using current pulses or potential pulses were determined by AFM and SEM microscopy. For BiSb, the effects of change from unipolar to reverse pulses and increase in cathodic current were shown as favorable. SEM images for BiSbTe confirmed the morphology modification by increasing the current pulses, while energy dispersive spectroscopy analyses indicate a dramatic change of composition.     

Separation and recovery of critical metal ions using ionic liquids

Separation and purification of critical metal ions such as rare-earth elements (REEs), scandium and niobium from their minerals is difficult and often determines if extraction is economically and environmentally feasible. Solvent extraction is a commonly used metal-ion separation process, usually favored because of its simplicity, speed and wide scope, which is why it is often employed for separating trace metals from their minerals. However, the types of solvents widely used for the recovery of metal ions have adverse environmental impact. Alternatives to solvent extraction have been explored and advances in separation technologies have shown commercial establishment of liquid membranes as an alternative to conventional solvent extraction for the recovery of metals and other valuable materials. Liquid membrane transport incorporates solvent extraction and membrane separation in one continuously operating system. Both methods conventionally use solvents that are harmful to the environment, however, the introduction of ionic liquids (ILs) over the last decade is set to minimize the environmental impact of both solvent extraction and liquid membrane separation processes. ILs are a family of organic molten salts with low or negligible vapour pressure which may be formed below 100 ℃. Such liquids are also highly thermally stable and less toxic. Their ionic structure makes them thermodynamically favorable solvents for the extraction of metallic ions. The main aim of this article is to review the current achievements in the separation of REE, scandium, niobium and vanadium from their minerals, using ILs in either solvent extraction or liquid membrane processes. The mechanism of separation using ILs is discussed and the engineering constraints to their application are identified.     

Functionalization of mesoporous MCM-41 for the delivery of curcumin as an anti-inflammatory therapy

In this study, mesoporous silica nanoparticles (MSNs) composed of MCM-41 were synthesized and modified with amine groups (i.e., NH₂) to form NH_2/MCM-41, which was loaded with curcumin (CUR) to form CUR@NH₂/MCM-41 to create an efficient carriers in drug delivery systems (DDSs). The three samples (i.e., pure MCM-41, NH₂/MCM-41, and CUR@NH₂/MCM-41) were characterized using X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area, Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transition electron microscopy (TEM), and a thermogravimetric analyzer (TGA). The study investigated the effect of the carrier dose, CUR concentration, pH, and contact time on the drug loading efficiency (DLE%) by adsorption. The best DLE% for MCM-41 and NH₂/MCM-41 was found to be 15.78 and 80%, respectively. This data demonstrated that the Langmuir isotherm had a greater correlation coefficient (R²) of 0.9840 for MCM-41 and 0.9666 for NH₂/MCM-41 than the Freundlich and Temkin isotherm models. A pseudo-second-order kinetic model seems to fit well with R² = 0.9741 for MCM-41 and R² = 0.9977 for NH₂/MCM-41. A phosphate buffer solution (PBS) with a pH of 7.4 was utilized to study CUR release behavior. As a result, the full release after 72 h was found to have a maximum of 74.1% and 29.95% for pure MCM-41 and NH₂/MCM-41, respectively. The first-order, Weibull, Hixson-Crowell, Korsmeyer-Peppas, and Higuchi kinetic release models were applied to releasing CUR from CUR@MCM-41 and CUR@NH₂/MCM-41. The Weibull kinetic model fit well, with R² = 0.944 and 0.96912 for pure MCM-41 and NH₂/MCM-41, respectively.     

Preparation of a platelike carbon nanomaterial using MgO as a template

A carbon nanomaterial in the form of hollow hexagonal platelets with shells of disordered graphene layers has been synthesized through CH₄ pyrolysis on pseudomorphic hexagonal MgO platelets 1–2 μm in average size, followed by dissolution of the magnesium oxide. The material has a specific surface area above 1300 m²/g, specific pore volume of 3.23 cm³/g, and resistivity of 0.08 Ω cm.